How to use the maestral.sync.oauth.OAuth2Session function in maestral

def __init__(self, parent, reason=EXPIRED):
        super(self.__class__, self).__init__(parent=None)
        uic.loadUi(RELINK_DIALOG_PATH, self)

        # import OAuth2Session here because of ~40 MB memory footprint
        from maestral.sync.oauth import OAuth2Session

        self._parent = parent
        self.auth_session = OAuth2Session()

        self.setModal(True)
        self.setWindowFlags(Qt.WindowTitleHint | Qt.CustomizeWindowHint)

        # format text labels
        if reason is self.EXPIRED:
            self.titleLabel.setText("Dropbox Access expired")
            formatted_text = self.infoLabel.text().format(
                "has expired", self.auth_session.get_auth_url())
        elif reason is self.REVOKED:
            self.titleLabel.setText("Dropbox Access revoked")
            formatted_text = self.infoLabel.text().format(
                "has been revoked", self.auth_session.get_auth_url())
        else:
            raise ValueError("'reason' must be RelinkDialog.EXPIRED or "
                             "RelinkDialog.REVOKED.")

def on_verify_token_finished(self, res):

        from maestral.sync.oauth import OAuth2Session

        if res == OAuth2Session.Success:
            self.auth_session.save_creds()
            self.lineEditAuthCode.setText(self.VALID_MSG)
            QtWidgets.QApplication.processEvents()
            QtCore.QTimer.singleShot(200, self._parent.restart)
        elif res == OAuth2Session.InvalidToken:
            self.lineEditAuthCode.setText(self.INVALID_MSG)
            self.set_ui_idle()
        elif res == OAuth2Session.ConnectionFailed:
            self.lineEditAuthCode.setText(self.CONNECTION_ERR_MSG)
            self.set_ui_idle()

def on_link(self):
        self.auth_session = OAuth2Session()
        self.auth_url = self.auth_session.get_auth_url()
        prompt = self.labelAuthLink.text().format(self.auth_url)
        self.labelAuthLink.setText(prompt)

        self.stackedWidget.fadeInIdx(1)
        self.pushButtonAuthPageLink.setFocus()

def __init__(self):

        # get Dropbox session
        self.auth = OAuth2Session()
        if not self.auth.load_token():
            self.auth.link()
        self._last_longpoll = None
        self._backoff = 0
        self._retry_count = 0

        # initialize API client
        self.dbx = dropbox.Dropbox(self.auth.access_token, session=SESSION,
                                   user_agent=USER_AGENT, timeout=60)

def pending_link():
        """Bool indicating if auth tokens are stored in the system's keychain."""
        auth_session = OAuth2Session()
        return auth_session.load_token() is None

def __init__(self, timeout=_timeout):

        # get Dropbox session
        self.auth = OAuth2Session()
        if not self.auth.load_token():
            self.auth.link()
        self._timeout = timeout
        self._last_longpoll = None
        self._backoff = 0
        self._retry_count = 0

        # initialize API client
        self.dbx = dropbox.Dropbox(
            self.auth.access_token,
            session=SESSION,
            user_agent=USER_AGENT,
            timeout=self._timeout
        )

def on_verify_token_finished(self, res):

        if res == OAuth2Session.Success:
            self.auth_session.save_creds()

            # switch to next page
            self.stackedWidget.slideInIdx(2)
            self.pushButtonDropboxPathSelect.setFocus()
            self.lineEditAuthCode.clear()  # clear since we might come back on unlink

            # start Maestral after linking to Dropbox account
            self.mdbx = Maestral(run=False)
            self.mdbx.get_account_info()
        elif res == OAuth2Session.InvalidToken:
            msg = "Please make sure that you entered the correct authentication token."
            msg_box = UserDialog("Authentication failed.", msg, parent=self)
            msg_box.open()
        elif res == OAuth2Session.ConnectionFailed:
            msg = "Please make sure that you are connected to the internet and try again."